Decision-makers believed eradication was possible because Mycoplasma bovis was ``not widespread'', infected properties were all connected through animal movements and there was just one strain of the disease, but acknowledged it would be challenging and required collaboration.

If successful, New Zealand would be the first country in the world to eradicate it.

The cull, of about 126,000 cattle in addition to the 26,000 already under way, would take place over one to two years.

Agriculture and Biosecurity Minister Damien O'Connor said it was important all farmers supported the operation.

``We all agree that while there remains a chance to get rid of this disease, we should take it. It's the only chance we'll get,'' Mr O'Connor said.

Southland Federated Farmers meat and wool chairwoman Bernadette Hunt said a better job had to be done in supporting those who were having to ``make a really big sacrifice for the future of New Zealand''.

``I think there's been a really sad tendency to demonise people that have become part of the testing process,'' she said.

Mrs Hunt and her husband, Alistair, who farm near Gore, received animals from an infected property which then tested negative right from the initial test.

Despite their property being cleared, she had heard comments that people would not buy stock from them. That rumour mill and gossip was ``incredibly hurtful''.

``As a rural community, we need to get in behind people a lot better,'' Mrs Hunt said.

There were a huge number of farms being tested that might never have the disease yet the farmers were ``demonised.''

It was going to be a long process and the only way the farming sector would get through it was if it was united in the fight, whether caught up in the process or not, she said.

Mycoplasma bovis could have serious effects on cattle, including mastitis, abortion, pneumonia and arthritis.

It was difficult to diagnose and control and Mr O'Connor cautioned it was possible at some stage ``we may have to let the fight go and learn to manage it in our herds''.

There was a set of reassessment measures that, if met, would prompt a re-evaluation of the plan.

Those included finding the disease was more widespread than surveillance and modelling anticipated, or a property was found that predated the earliest known infection of December 2015.

Mr O'Connor said he had asked the Ministry for Primary Industries to revisit the compensation process and a new ``streamlined'' approach had been developed for those whose animals were culled to enable a substantial payment ``within a matter of days''.

The full cost of phased eradication over 10 years was projected at $886 million. Of that, $16 million was loss of production and was borne by farmers and $870 million was the cost of the response, including compensation.

The Government would meet 68% of that cost and DairyNZ and Beef + Lamb New Zealand would meet 32%.

Speaking to affected farmers in recent weeks, Prime Minister Jacinda Ardern said it was obvious it had taken a toll, but standing back and allowing the disease to spread would simply create more anxiety for all farmers.

``This is a tough call - no-one ever wants to see mass culls. But the alternative is to risk the spread of the disease across our national herd,'' she said.

Federated Farmers national president Katie Milne said there was no doubt the decision would cause pain and anguish for more farmers.

But the organisation believed getting rid of the disease was preferable to living with it, for years on end, and probably without any compensation available for farmers in the future when it did hit and could not be controlled.

Ms Ardern and Mr O'Connor will visit the dairy farm of Leo Bensegues in Morven today to discuss the plan for phased eradication of M.bovis.